Modded the X850XT. Only did VGPU.
IGPU is strange as the resistor which defines this is already much lower than mentioned on the site. So i'm not touching that one for now. Can Always be pencil modded later.
After mod VGPU read 1.465V @ around 10K on pot.
I've now increased it to 1.5V. Did a quick run of AM3 @ 630MHz core - using rivatuner - but artifacts and lockup so I guess you'll need to increase it to >1.50V to get more out of it, there's still room.

But I leave the turning to you, that way it's not me blowing up the card
VGPU on this card is more stable under load than the 8800GTX

@ Albrecht : found the cable for your Kingston WiFi drive in one of my crates.